re PR c++/5748 (g++ dies with optimization)

	PR c++/5748
	* stmt.c (expand_anon_union_decl): Set TREE_USED on the anon union
	decl if any of elements was TREE_USED.

	* g++.dg/opt/anonunion1.C: New test.

From-SVN: r49971

gcc/ChangeLog

+2002-02-22  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/5748
+	* stmt.c (expand_anon_union_decl): Set TREE_USED on the anon union
+	decl if any of elements was TREE_USED.
+
 2002-02-22  Alexandre Oliva  <aoliva@redhat.com>
 
 	* config/sparc/sol2.h: Don't include sys/mman.h.

gcc/stmt.c

@@ -4201,6 +4201,11 @@ expand_anon_union_decl (decl, cleanup, decl_elts)
       tree cleanup_elt = TREE_PURPOSE (t);
       enum machine_mode mode = TYPE_MODE (TREE_TYPE (decl_elt));
 
+      /* If any of the elements are addressable, so is the entire
+	 union.  */
+      if (TREE_USED (decl_elt))
+	TREE_USED (decl) = 1;
+
       /* Propagate the union's alignment to the elements.  */
       DECL_ALIGN (decl_elt) = DECL_ALIGN (decl);
       DECL_USER_ALIGN (decl_elt) = DECL_USER_ALIGN (decl);

gcc/testsuite/ChangeLog

+2002-02-22  Jakub Jelinek  <jakub@redhat.com>
+
+	* g++.dg/opt/anonunion1.C: New test.
+
 2002-02-22  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* g++.dg/template/qualttp19.C: New test.

gcc/testsuite/g++.dg/opt/anonunion1.C

+// PR c++/5748
+// This testcase ICEd because used flag from the anon union variables
+// was not propagated back to the anon union itself, causing addressof
+// not to be replaced with stack slot.
+// { dg-do compile }
+// { dg-options "-O2" }
+
+struct A {
+  A ();
+  ~A ();
+  int foo ();
+  int bar (void *x, int y);
+};
+
+int A::foo()
+{
+  union {
+    int a;
+    int b;
+  };
+
+  if (bar (&a, sizeof (int)) != 32)
+    return 16;
+  return 0;
+}